Conventionally, there is known a conference system using an information processing apparatus having a built-in display device. In such a conference system, there are cases where the information processing apparatus uses a display device connected externally (hereinafter, “external display”), which is different from the display device that is built in the information processing apparatus (hereinafter, “internal display”). In this case, the information processing apparatus switches the display device and uses the display device after switching. Cases where the display devices are switched are as follows. For example, there is a case where an external display having a different display device from that of the internal display, is connected to the information processing apparatus, and a case where an external display having a different resolution from that of the internal display is connected to the information processing apparatus.
With respect to a transmission terminal that is connected to a display device and that outputs image data, there is known a technology of appropriately displaying image data and auxiliary information according to the capability of the display (see, for example, Patent Literature 1).
In the conventional technology, there are cases where after switching from the internal display to the external display, the displayed image becomes smaller than the display area of the external display. This often occurs when the information processing apparatus specifies a resolution that is lower than the resolution of the external display, and the image is displayed on the external display according to the low resolution, and scaling (enlargement) display is not performed. When the image is displayed in the display area of the external display according to the low resolution, a margin such as a black frame is added on the outside of the original image, and the user may feel like something is wrong with the display.
For example, in a regular PC (Personal Computer), when the image displayed after switching from the internal display to the external display, is smaller than the display area of the external display, the user can address this situation by activating a tool for controlling the graphic driver, and making a setting to perform scaling display.
However, in a special purpose information processing apparatus such as a TV conference device or a small-sized terminal, it is not assumed that a tool for controlling the graphic driver will be used, and a graphic driver that is set in advance to perform scaling display is generally incorporated. In this case, at the time of shipping the information processing apparatus, the manufacturer of the graphic driver can incorporate a graphic driver ensuring that scaling display can be performed on the resolution supported by an internal display built in the special purpose information processing apparatus.
However, an external display is often prepared by the user, and there are various types of resolutions supported by the external display, compared to that of a built-in display. Therefore, when a resolution that is not supported by the internal display is directly specified, it may not be possible for the process of switching the display to the external display, the process of changing the resolution, and scaling process to be executed all at once in time. That is, even when a graphic driver that is set in advance to perform scaling display is incorporated in the information processing apparatus, the scaling process may be unsuccessful.